Abby Lee Miller, best known for her role as the tough-as-nails teacher on the reality show Dance Moms, is already sharing her cancer journey publicly. On Sunday, Miller posted a selfie to Instagram of her wearing a hospital gown with an IV needle in her hand.

In the caption, Miller expressed thanks to those who helped her get the medical attention she needed.

"So much gratitude and love for those who listened, those who looked deeper and those who leapt into action," she wrote. "So much more I wish I could say......about how quickly your life can change at the hands of others."

"Those who leaped into action" undoubtedly includes Hooman M. Melamed, M.D., a surgeon who treated Miller when she came to him with extreme neck pain. The pain eventually escalated to paralysis before Miller underwent a five-hour spinal surgery, he told SELF.

Dr. Melamed emphasized what a dangerous position the reality star was in when she first arrived for treatment."If she waited, she would have died," he said. "Her blood pressure was plummeting and her kidneys were starting to fail."

After the surgery, a tissue sample led to Miller's preliminary diagnosis of Burkitt lymphoma, a form of non-Hodgkin's lymphoma.

Burkitt lymphoma is a type cancer that affects the lymph system, which is part of the immune system. Because lymph tissue is found all over the body, the cancer can start in many places. However, most cases of this type of cancer don't start as neck pain. The fact that she experienced severe pain suggests Miller has an aggressive form of the disease, Michael Jain, M.D., a hematologist with Moffitt Cancer Center, told SELF previously.

Miller will need another spinal surgery, Dr. Melamed told People, but her condition is improving. She's regained some movement in her arms, toes, and legs, which is a positive sign.

“I almost cried when I saw she could move a little,” Dr. Melamed told SELF previously. “Hopefully, she’ll be able to walk again.”